Preparation of dialkoxyvinylboranes



tates t his 3,024,265 Patented Mar. 6, 1962 This invention relates to an improved process for the preparation of dialkoxyvinylboranes.

it is the principal object of the present invention to provide an improved process for the preparation of dialkoxyvinylboranes which is rapid and economically desirable.

Other objects of the invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various Ways in which the principle of the invention may be employed.

Broadly stated, the present invention comprises the method of preparing dialkoxyvinylboranes having the general formula which comprises heating a metal trialkoxvinylborate having the general formula in an inert solvent until said metal trialkoxyvinylborate is thermally decomposed and distilling substantially pure dialkoxyvinylborane as it is formed from said solvent, said solvent being selected from the group consisting of anhydrous hydrocarbons, chlorinated aromatic hydrocarbons, and ethereal solvents having a boiling point greater than about 150 C., and when R is an alkyl group and M is a material selected from the group consisting of MgCl and MgBr.

It is of interest to note that the present invention can he used to prepare the dialkoxyvinylboranes in a continuous manner. Distillation of the dialkoxyvinylboranes may be started immediately upon reaching the decomposition temperature of the vinyltrialkoxyborate, and by maintaining a balanced continuous feed and discharge system while maintaining the required decomposition temperature the process can be performed continuously. Still further, the present process can be carried out at atmospheric or reduced pressures.

Prior methods for recovering dialkoxyvinylboranes from metal trialkoxyvinylborates were more costly and time consuming. The present invention is relatively simple and it eliminates the necessity for additional reactants other than the metal trialkoxyvinylborates and is easily carried out in conventional distillation equipment.

The metal trialkoxyvinylborates used as the starting material in the present invention, as noted above, have the general formula H C=CHB(OR) M, where R is an alkyl group and M is either MgCl or MgBr. One easy method of making them is by the reaction of the vinylmagnesium chloride or bromide with a trialkylborate ester. The number of carbon atoms in the alkyl group of the ester is immaterial. Trimethyl borate or trinonyl borate or borate esters having even longer carbon chains can be made and the corresponding metal trialkoxyvinylborate can be derived from these esters. For the sake of economy and availability in the preferred embodiment of our invention we use metal trialkoxyvinylborates, the alkyl portion of which contains from 1 to 4 carbon atoms. However, it is again emphasized that the size-of the alkyl group is immaterial to the present process.

Any anhydrous hydrocarbon, chlorinated aromatic hydrocarbon or ethereal solvent having a boiling point higher than about 150 C. which is inert to the metal trialkoxyvinylborate is applicable to the present invention. The following list is illustrative of this group of compounds:

Mineral oil Diethylbenzene Kerosene Bis Z-methoxyethyl) ether Diphenylether Diisopropylbenzene 1,2-bis (2-methoxyethoxy) ethane Bis (Z-methoxyethoxy) ethyl] ether p-Dichlorob enzene So that the'pres'ent invention can be more easily understood, the following examples are given for illustrative purposes:

A three-liter, 3-necked, round-bottomed flask equipped with a motor stirrer, a pot thermometer, anitrogen inlet tube and a distillation assembly was used in each of the following examples. The apparatus was flushed with-dry,

high purity nitrogen each time to make sure the equipment'was dry and oxygen free. The nitrogen stream was maintained during each of the examples to ensure an inert atmosphere.

One hundred grams of chloromagnesium trimethoxyvinylborate was placed in the flask with 800 ml. of light mineral oil and the mixture was heated. At a pot temperature of 154 C. distillate started to collect. The heat was increased 200 C. where about of the distillate was recovered. The heat was then slowly increased to 240 C. and the remainder of the distillate was recovered. The total yield of distillate was 43.5 grams or about of theory. Chemical analysis'yielded the following data.

Percent B in CH =CHB(OCH Calculated: 10.84%. Found=10.69%.

One hundred and fifty grams of bromomagnesium triisopropoxyvinylborate was placed in the flask with 1200 ml. of light mineral oil. At a pot temperature of 163 C. the first of the distillate was observed. The heat was slowly increased to 250 C. and after about 30 minutes the distillate stopped coming over and the temperature was lowered. The total yield of product was 59 grams,

or about 80% of the theoretical amount. Chemical analysis yielded the following data.

Percent B in CH =CHB(OC H Calculated=, 6.94%. Found=6.76%.

Calculated:

Two hundred grams of bromomagnesium tri-n-butoxyvinylborate was placed in the flask with 1500 ml. of light mineral oil. At a pot temperature of 166 C. the first portion of the distillate was observed and heating was continued until the pot temperature reached from 240 C.

.to 260 C. When the distillate stopped coming over,

after about 60 minutes, the heating was discontinued. The total yield of product was 84.8 grams, about 79% of theoretical. Chemical analysis yielded the following data.

Percent B in CH =CHB(OC H Calculated= 5.58%. Found=5.49%.

The above examples were repeated using other solvents such as bis(2-methoxyethyl)ether, diphenylether and diisopropylbenzene with substantially the same results.

Other modes of applying the principle of the invention may be employed change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

We, therefore, particularly point out and distinctly claim as our invention:

1. The method of preparing dialkoxyvinylboranes having the general formula which comprises heating a metal trialkoxyvinylborate having the general formula H C=CHB(OR) M which comprises heating a metal trialkoxyvinylborate having the general formula in an inert solvent until said metal trialkoxyvinylborate is thermally decomposed and distilling substantially pure dialkoxyvinylborane as it is formed from said solvent, said solvent being selected from the group consisting of anhydrous hydrocarbons, chlorinated aromatic hydrocarbons and ethereal solvents having a boiling point greater than about C. and where R is an alkyl group containing from 1 to 4 carbon atoms and M is a material selected from the group consisting of MgBr and MgCl.

3. The method of preparing dialkoxyvinylboranes having the general formula which comprises heating at from about 150 C. to about 275 C. a metal trialkoxyvinylborate having the general formula H C=CHB(OR) M in mineral oil until said metal trialkoxyvinylborate is thermally decomposed and distilling substantially pure dialkoxyvinylborane as it is formed from said mineral oil, where R is an alkyl group containing from 1 to 4 carbon atoms and M is a material selected from the group consisting of MgCl and MgBr.

4. The method of preparing dimethoxyvinylborane which comprises heating chloromagnesium trimethoxyvinylborate in mineral oil at a temperature of from about 150 C. ot about 250 C. until said chloromagnesiumtrimethoxyvinylborate is thermally decomposed and distilling substantially pure dimethoxyvinylborane as it is formed from said mineral oil.

5. The method of preparing diethoxyvinylborane which comprises heating chloromagnesium triethoxyvinylborate in mineral oil at a temperature of from about 150 C. to about 250 C. until said chloromagnesium triethoxyvinylborate is thermally decomposed and distilling substantially pure diethoxyvinylborane as it is formed from said mineral oil.

6. The method of preparing diisopropoxyvinylborane which comprises heating bromomagnesium triisopropoxyvinylborate in mineral oil at a temperature of from about C. to about 250 C. until said bromomagnesiumtriisopropoxyvinylborate is thermally decomposed and distilling substantially pure diisopropoxyvinylborane as it is formed from said mineral oil.

7. The method of preparing di-n-butoxyvinylborane which comprises heating bromomagnesium tri-n-butoxyvinylborate in mineral oil at a temperature of from about 160 C. to about 260 C. until said bromomagnesium tri-n-butoxyvinylborane is thermally decomposed and distilling substantially pure dibutoxyvinylborane as it is formed from said mineral oil.

No references cited. 

1. THE METHOD OF PREPARING DIALKOXYVINYLBORANES HAVING THE GENERAL FORMULA 